Oct. 30, 2008, marked the 70th anniversary of Orson Welles’ legendary radio broadcast of “The War of the Worlds,” which sparked a nationwide panic, causing many Americans to believe an actual Martian invasion was under way.
Directed and narrated by Welles, the hour-long broadcast aired Oct. 30, 1938, as a Halloween-themed episode of CBS’ radio series, Mercury Theatre on the Air.
The performance was an adaptation of H.G. Wells’ sci-fi novel The War of the Worlds, and was delivered in such a ways as to simulate a live news report of a Martian invasion.
Wikipedia has an article about the broadcast and historians’ differing views of the reaction to it: